I know how you feel, I had the same thing happen to a quilt I made for my daughter. It was black, white and red, more of a young persons color and design. I washed it before giving and it shrunk 5-6 inches. I was very upset, had to work really hard not to cry. The shrinkage ruined the young design, young people don't like the traditional quilt puckering. Well, I guess I should say my two daughters don't like the puckered traditional look. Personally, I like the puckered look. Is your concern that it puckered or that it shrunk too small for your MIL's bed?